JP7112578B1 - Method for producing quinacridone solid solution pigment - Google Patents

Abstract

Kind Code: A1 A quinacridone solid solution pigment of various hues including unique intermediate hues is realized, and a pigment dispersion having a uniform particle size, in which the saturation of liquid chromaticity is suppressed, is provided. The method includes a step of producing a crude quinacridone solid solution, a step of drying the solid solution, a step of heating the dried crude quinacridone solid solution in a liquid medium to form a pigment, and a step of treating the pigmented pigment with a quinacridone pigment derivative. Then, in the production process, a crude quinacridone solid solution containing water in a solid solution in which the ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 85:15 to 50:50 or 20:80 to 50:50 is obtained. Obtaining a powdery crude quinacridone solid solution having a content of less than 1%, in the pigmentation step, pigmenting the powdery crude quinacridone solid solution in a liquid medium at a temperature above 70°C to 120°C, in the treatment step 3. A production method of obtaining a quinacridone solid solution pigment to which the derivative is added by adding a quinacridone pigment derivative after cooling the liquid medium to a temperature of 70° C. or less. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a method for producing a quinacridone solid solution pigment, a quinacridone solid solution pigment, a pigment dispersion and an inkjet ink.

Quinacridones are high-performing synthetic pigments with brilliant colors and weatherability, typically exhibiting red to violet hues, whose hue can be influenced by substituents on the conjugated rings and crystal structure. Are known. Quinacridone solid solution pigments, which are one field of quinacridone pigments, have been extensively studied in the field of organic pigments. For example, a quinacridone pigment comprising a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone is known. Various proposals have been made for realizing good color and good pigment properties for quinacridone solid solution pigments composed of unsubstituted quinacridone and 2,9-dimethylquinacridone (see Patent Documents 1 to 3). .

In Patent Document 1, a colored product obtained by applying a quinacridone solid solution pigment composed of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone has high chroma and has a bluish color. A method for producing quinacridone solid solution pigments has been proposed. Further, in Patent Document 2, a colored product obtained by applying a quinacridone solid solution pigment composed of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone has high chroma and a yellow tint. A method for producing quinacridone solid solution pigments has been proposed. These conventional techniques were developed by the applicant of the present application, and according to these conventional techniques, it is possible to control the particle size of the quinacridone solid solution pigment to a desired size in addition to obtaining a highly saturated color. can. As another prior art, Patent Document 3 proposes a quinacridone solid solution pigment composed of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone, which is said to have a bright yellow color and excellent storage stability.

Japanese Patent No. 6697571 WO2019/187058 Japanese Patent No. 6769577

As described above, the prior art has realized bluish quinacridone solid solution pigments and yellowish quinacridone solid solution pigments, and the quinacridone solid solution pigments proposed by the prior art can be used in a wide range of applications. is. When applied to a colorant for an inkjet ink, it is desired that the particles are fine and have a uniform particle size. It is preferred to utilize quinacridone solid solution pigments provided by technology that allows for size control.

In view of the situation of the prior art described above, the inventors of the present invention firstly found that the bluish quinacridone solid solution pigment and the yellowish quinacridone solid solution pigment developed by the prior art cannot effectively express the color, which can be said to be an intermediate color. , recognized that it is necessary to be able to provide a quinacridone solid solution pigment with a unique purple color (hue) that has a moderate yellowish and bluish tinge. In addition to providing a quinacridone solid solution pigment that can realize various colors, the present inventors have found that, for example, when it is applied to a colorant for inkjet ink, the quality of printed matter can be further improved. , the average particle size of fine pigments is controlled to a desired size, similarly to what has been achieved in the prior art, and there is a need for a technique for providing pigments with more uniform particle sizes. had the recognition of In contrast, the present inventors have found that there are problems as described below when conventional quinacridone solid solution pigments are applied to inkjet inks.

In recent years, the fields of application of printed matter obtained by the inkjet recording method have expanded, and in addition to small-sized printed matter such as office documents, pamphlets, and printed matter of photographs, large-sized signboards, exhibits, indoor or outdoor decorations, etc. , and its use for large-sized printed matter is expanding. Pigments are used as colorants for ink jet inks used for outdoor printed materials that are required to have excellent water resistance, weather resistance, and the like. Dispersion stability and storage stability of pigments are fundamental technical issues to be achieved in water-based pigment dispersions and water-based inkjet inks using pigments. The size of pigments used in inkjet inks depends on the application, but is said to be, for example, about 50 nm to 200 nm. From the viewpoint of ink ejection stability, pigments with uniform particle diameters are also desired. It is Technical problems such as the dispersion stability of pigments become extremely important when the particle size of the pigment applied to the ink is large.

According to the technique described in the aforementioned Patent Document 1, the particle size of the obtained quinacridone solid solution pigment can be appropriately controlled by adjusting the heating temperature in the pigmentation process. In addition, in the above-described prior art, when the powdery crude quinacridone solid solution is heated in a liquid medium to form a pigment, a quinacridone-based pigment derivative is added to enhance the effect of making the particles of the quinacridone solid solution pigment uniform. It is possible. In contrast, the present inventors have found that the addition of a quinacridone-based pigment derivative tends to reduce the saturation of liquid chromaticity. For these reasons, there is a need for a technique for providing a quinacridone solid solution pigment with superior properties in order to obtain higher quality prints when it is applied to, for example, an inkjet ink.

Accordingly, an object of the present invention is to provide solid solutions of unsubstituted quinacridones and 2,9-dimethylquinacridones of desired hues, including unique intermediate tints not found in conventionally provided quinacridone solid solution pigments. It is to realize a technology that can provide a quinacridone solid solution pigment. Another object of the present invention is to provide a quinacridone solid solution pigment whose average particle size is controlled and which has a uniform pigment particle size when applied to an aqueous pigment dispersion or ink. An object of the present invention is to provide a technique capable of realizing a new quinacridone solid solution pigment capable of effectively suppressing the tendency of liquid chromaticity in aqueous pigment dispersions to decrease in chroma. The object of the present invention is, for example, when applied to a colorant for water-based inkjet ink, it is possible to realize various desired colors and to provide printed matter with higher quality. An object of the present invention is to provide a quinacridone solid solution pigment having good stability.

The above problems of the prior art are achieved by the present invention described below.
[1] A step of producing a crude quinacridone solid solution, a drying step of drying the crude quinacridone solid solution, a pigmentation step of heating the dried crude quinacridone solid solution in a liquid medium to form a pigment, and converting the pigmented pigment into a quinacridone-based pigment. and a treatment step of treating with a derivative,
In the process for producing the crude quinacridone solid solution, diarylaminoterephthalic acid and dialkylarylaminoterephthalic acid are subjected to a co-cyclization reaction in polyphosphoric acid so that the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 85: Obtaining a crude quinacridone solid solution in a hydrous state containing water in a solid solution of 15 to 50:50 or 20:80 to 50:50,
in the drying step, drying the hydrous crude quinacridone solid solution to a moisture content of less than 1% to obtain a powdery crude quinacridone solid solution;
In the pigmentation step, the powdery crude quinacridone solid solution obtained above is heated at a temperature of over 70° C. to 120° C. in a liquid medium that does not dissolve the crude quinacridone solid solution to form a pigment,
In the treatment step, the heated liquid medium after pigmentation is cooled to a temperature of 70° C. or less, and then a quinacridone-based pigment derivative is added to obtain a quinacridone solid-solution pigment obtained by adding the quinacridone-based pigment derivative to the quinacridone solid-solution pigment. A method for producing a quinacridone solid solution pigment, characterized by obtaining

In addition, preferred embodiments of the above-described method for producing the quinacridone solid solution pigment of the present invention include the following.
[2] The diarylaminoterephthalic acid is 2,5-dianilinoterephthalic acid, the dialkylarylaminoterephthalic acid is 2,5-di(p-toluidino)terephthalic acid, and the quinacridone pigment The method for producing a quinacridone solid solution pigment according to the above [1], wherein the derivative is 2-phthalimidomethylquinacridone.

Further, another embodiment of the present invention includes the following.
[3] A quinacridone solid solution pigment obtained by the method for producing a quinacridone solid solution pigment according to [1] or [2] above.
[4] A pigment dispersion containing a quinacridone solid solution pigment, a pigment dispersant, and water, wherein the quinacridone solid solution pigment is the quinacridone solid solution pigment described in [3] above.
[5] Containing a quinacridone solid solution pigment, a pigment dispersant, and water, wherein the quinacridone solid solution pigment is contained in the quinacridone solid solution pigment described in [3] above or the pigment dispersion liquid described in [4] above. An inkjet ink, characterized in that it is a quinacridone solid solution pigment.

According to the present invention, it is possible to provide a quinacridone solid solution pigment composed of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone with a desired hue, including a unique intermediate hue not found in conventional quinacridone pigments. Become. Further, according to the present invention, it is possible to provide a quinacridone solid solution pigment whose average particle size can be appropriately controlled and which has good dispersion stability and storage stability when applied to an aqueous pigment dispersion or ink. . In addition, according to the present invention, when applied to an aqueous pigment dispersion or ink, the tendency of liquid chromaticity to decrease in chroma, which has sometimes occurred, can be effectively suppressed. It is possible to provide a quinacridone solid solution pigment having more uniform pigment particle diameters than the above. INDUSTRIAL APPLICABILITY According to the present invention, for example, a quinacridone solid solution pigment is provided that, when applied as a colorant for water-based inkjet inks, enables the realization of printed matter with a variety of desired colors and excellent quality.

Next, the present invention will be described in more detail by giving preferred modes for carrying out the invention. The inventors of the present invention made intensive studies to solve the above-described problems in the prior art, and as a result, obtained the following findings and completed the present invention.

First, in the quinacridone solid solution pigment consisting of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone, the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is set to 50:50, which has not been studied in the past. We considered the case where As a result, the inventors have found that a quinacridone solid solution pigment with a special color that has never existed before can be realized. Specifically, a stable quinacridone solid solution pigment with a unique purple color was obtained. According to the studies of the present inventors, this color is a unique tint that has never been realized in a quinacridone solid solution pigment composed of a solid solution of unsubstituted quinacridone and 2,9-dimethylquinacridone. As a result, in addition to the bluish quinacridone solid solution pigment and the yellowish quinacridone solid solution pigment proposed and provided by the present applicant, it is possible to realize an intermediate color tone. By expanding the range of selection, we can expect to expand the use of quinacridone solid solution pigments in the future.

In addition to providing the above-mentioned quinacridone solid solution pigment with a new color, the present inventors have found a quinacridone solid solution pigment that provides the following effects, resulting in the present invention. As described above, according to the prior art proposed by the applicant of the present application, it is possible to control the particle size of the quinacridone solid solution pigment to a desired size. Furthermore, by adding a quinacridone-based pigment derivative, the effect of making the particles of the quinacridone solid solution pigment uniform can be enhanced. However, according to further studies by the present inventors, when a quinacridone solid solution pigment to which a quinacridone-based pigment derivative is added is used as a pigment dispersion, the chromaticity of the liquid tends to be low. There was room for improvement. In addition, when applied to a colorant for inkjet inks, pigments with particle diameters as uniform as possible are desired, and there is room for improvement in this respect as well.

As a result of studies conducted by the present inventors to address the above problems, in the conventional method for producing a quinacridone solid solution pigment, a quinacridone pigment derivative is added when the crude quinacridone solid solution is heated to form a pigment. The inventors have found that the above-described problems can be solved without affecting the color by simply changing the timing of adding the pigment derivative, leading to the present invention.

"Quinacridone solid solution pigment" means a pigment that exists in a uniform solid state in a mixed state in which a plurality of different quinacridone pigment molecules are dissolved, and is not simply a mixture of a plurality of different quinacridone pigments. It is known that properties such as color change by forming a solid solution. An object of the present invention is to produce a "solid solution of unsubstituted quinacridone and 2,9-dialkylquinacridone". These are alone, and unsubstituted quinacridone is C.I. I. Pigment Violet 19 and 2,9-dialkylquinacridones are C.I. I. Pigment Red 122, respectively. The manufacturing method of the present invention will be described below.

<Method for producing quinacridone solid solution pigment>
The method for producing a quinacridone solid solution pigment of the present invention comprises a step of producing a crude quinacridone solid solution, a drying step of drying the crude quinacridone solid solution, and a pigmenting step of heating the dried crude quinacridone solid solution in a liquid medium to form a pigment. and a treatment step of adding a quinacridone-based pigment derivative to the pigment that has been converted into a pigment. In the above crude quinacridone solid solution production process, diarylaminoterephthalic acid and dialkylarylaminoterephthalic acid are subjected to a co-cyclization reaction in polyphosphoric acid so that the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 85: A crude quinacridone solid solution in a hydrous state containing water in a 15-50:50 or 20:80-50:50 solid solution is obtained. In the production method of the present invention, it is possible to obtain quinacridone solid solution pigments in a wider range of ratios than in the prior art, including cases where the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 50:50. Thus, it becomes possible to provide colorants with a wider variety of colors than the conventional technology.

In the method for producing a quinacridone solid solution pigment of the present invention, the crude quinacridone solid solution in a water-containing state is dried to reduce the water content to less than 1% before forming a pigment using the crude quinacridone solid solution. and a drying step to obtain a powdery crude quinacridone solid solution. By including the drying step, the particle size of the produced pigment can be controlled.

In the method for producing a quinacridone solid solution pigment of the present invention, in the pigmentation step, the powdery crude quinacridone solid solution obtained after the drying step is heated at a temperature of more than 70°C to 120°C in a liquid medium that does not dissolve the crude quinacridone solid solution. , preferably at a temperature of more than 70 ° C. to about 110 ° C. to heat to pigment, cool the heated liquid medium after the pigmentation to a temperature of 70 ° C. or less, add a quinacridone pigment derivative, A quinacridone solid solution pigment is obtained by adding a quinacridone pigment derivative to a quinacridone solid solution pigment. As will be described later, with the configuration described above, when a pigment dispersion liquid is prepared using the obtained quinacridone solid solution pigment, it is possible to suppress the tendency of the liquid chromaticity to decrease in saturation. In addition, a quinacridone solid solution pigment having a more uniform particle size in the pigment dispersion can be obtained. As a result, for example, by using the quinacridone solid solution pigment of the present invention as a colorant for inkjet inks, it is possible to realize inks of various colors and to obtain printed matters of higher quality. Furthermore, as will be described later, the quinacridone solid solution pigment obtained by the present invention exhibits excellent storage stability and dispersibility when applied to a pigment dispersion or ink. is useful as

The manufacturing process for obtaining the crude quinacridone solid solution and the drying process for drying the obtained crude quinacridone solid solution, which constitute the method for manufacturing the quinacridone solid solution pigment of the present invention, are described in the aforementioned Patent Documents 1 and 2. It is almost the same as the method. The method for producing a quinacridone solid solution pigment of the present invention differs from the above-described prior art in that a crude quinacridone solid solution is heated in a liquid medium that does not dissolve the crude quinacridone solid solution to form a pigment, and after the pigmentation, the heated After cooling the liquid medium to a temperature of 70° C. or less, a quinacridone pigment derivative is added to obtain a quinacridone solid solution pigment in which the quinacridone pigment derivative is added to the quinacridone solid solution pigment. As for the heating temperature and heating time during pigmentation, and the liquid medium that does not dissolve the crude quinacridone solid solution used in pigmentation, any of the conditions and liquid medium used in the production of conventional quinacridone solid solution pigments can be used. can. For example, liquid media in which the crude quinacridone solid solution used for pigmentation is not dissolved include dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, ethanol, propanol, butanol and ethylene glycol.

In the present invention, a crude quinacridone solid solution is heated in a liquid medium to form a pigment, the heated liquid medium after the pigmentation is cooled, and a quinacridone pigment derivative is added to the liquid medium after cooling. A quinacridone-based pigment derivative is added to the quinacridone solid solution pigment that has been completed. The temperature of the liquid medium cooled after pigmentation is not particularly limited as long as it is a temperature lower than the heating temperature during pigmentation, specifically a temperature of 70° C. or less. For example, it is preferable to set the temperature to about room temperature of 40° C. or less. As described above, in the method for producing a quinacridone solid solution pigment of the present invention, the treatment of adding the quinacridone pigment derivative can be carried out at a temperature as low as room temperature, so that the treatment can be carried out safely. In addition, since it can be cooled down to about room temperature, it also has the advantage of not requiring special equipment or materials for temperature control. Further, according to the configuration of the present invention, before the quinacridone pigment derivative is added, the crude quinacridone solid solution is in a state where the pigmentation is completed. Since it is a pigment with a specific color that is uniform, even if a pigment derivative is added and treated after that, it will not have a large effect on the already uniform particle size or specific color. Conceivable. As a result, when the quinacridone solid solution pigment obtained by the method for producing a quinacridone solid solution pigment of the present invention is applied to an inkjet ink, etc., the printed matter is superior to the case of using a conventional solid solution pigment as a colorant. can enable the provision of

<Pigment Dispersion Containing Quinacridone Solid Solution Pigment>
When the quinacridone solid solution pigment of the present invention obtained as described above is used as a pigment dispersion containing a pigment dispersant and water, the pigment has a uniform particle size and exhibits a decrease in chroma in liquid chromaticity. is suppressed, and is useful, for example, as a colorant for inkjet inks. The pigment dispersant used above is not particularly limited, and any conventionally known dispersant used in inkjet inks using a pigment as a colorant can be used.

<Inkjet ink containing quinacridone solid solution pigment>
The inkjet ink of the present invention is characterized by containing the above-described quinacridone solid solution pigment of the present invention, a pigment dispersant, and water. When preparing an inkjet ink, a pigment dispersion containing the quinacridone solid solution pigment of the invention can be used as a colorant.

In the inkjet ink of the present invention, since the quinacridone solid solution pigment of the present invention is used as the coloring agent, the liquid chromaticity does not tend to decrease in chroma. By appropriately adjusting the mass ratio of, a colored product with a desired color selected from a yellowish hue, a bluish hue, and a moderate hue between yellowish and bluish hues that has not existed in the past becomes possible to obtain. The addition amount of the quinacridone solid solution pigment constituting the inkjet ink of the present invention is not particularly limited, and may be contained within a conventionally known range. Specifically, it may be about 0.5 to 30% by mass, more preferably about 4 to 10% by mass, based on 100% by mass of the inkjet ink. If the amount added is less than 0.5% by mass, the print density may not be ensured. may deteriorate the ejection stability of the ink. When the quinacridone solid solution pigment of the present invention is used as a colorant for an inkjet ink, the particle size of the quinacridone solid solution pigment in the ink is more uniform than when a conventional quinacridone solid solution pigment is used, resulting in good dispersion. It was confirmed that the

The present invention will be further described below with reference to examples and comparative examples. "%" and "parts" below are based on mass unless otherwise specified.

[Preparation of quinacridone solid solution pigment]
[Examples 1 to 3]
(Example 1)
First, 32.8 g of 85% phosphoric acid was weighed into a 100 ml separable flask, and 49.4 g of anhydrous phosphoric acid was added to prepare 84.0% polyphosphoric acid. Then, when the internal temperature drops to about 100° C., add 10.2 g of 2,5-di(p-toluidino)terephthalic acid (DM-DATA), then 10.2 g of 2,5-dianilinoterephthalic acid (DATA). was added gradually. After completion of the addition, a cocyclization reaction was carried out at 120° C. for 4 hours. After completion of the reaction, the reaction solution obtained above was put into a 500 ml beaker filled with 200 ml of room temperature water. After filtration and washing with water, the mixture was transferred to a 1 L beaker, 500 ml of water was added and stirred, and caustic soda was added to adjust the pH to 7-8. This was filtered and washed with hot water to obtain a crude quinacridone solid solution containing water. This crude quinacridone solid solution had a mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone of 50:50.

The wet crude quinacridone solid solution obtained above was dried at 80° C. overnight to a moisture content of less than 1%. After drying, it was pulverized to obtain 18.0 g of crude quinacridone solid solution powder. Observation of the obtained powder with a transmission electron microscope revealed that the average particle size of the long axis was about 20 nm.

Next, using dimethyl sulfoxide (DMSO) as a liquid medium that does not dissolve the above powder, the crude quinacridone solid solution was pigmented as follows. Specifically, 7.0 g of the crude quinacridone solid solution powder obtained as described above and 52.5 g of dimethyl sulfoxide were charged into a 100 ml separable flask, heated to 100° C. over 30 minutes, and It was heat-treated at room temperature for 3 hours to form a pigment.

After heating and pigmenting as described above, the liquid medium was cooled to a temperature of 40° C. or less. Then, 0.21 g of 2-phthalimidomethylquinacridone powder (addition ratio: 3%), which is a quinacridone pigment derivative, was added to the liquid medium after cooling, and the mixture was further treated for 1 hour while stirring. After the addition of the pigment derivative and the stirring treatment, the mixture was filtered, washed with hot water and water until the filtrate became colorless, dried at 80° C., and treated with the quinacridone-based pigment derivative of this example. A solid solution pigment powder was obtained.

It was confirmed by powder X-ray diffraction that the pigment obtained by adding a quinacridone-based pigment derivative to the quinacridone solid solution pigment obtained as described above is the quinacridone solid solution targeted by the present invention. . Specifically, the powder of the quinacridone solid solution pigment to be measured is packed in a predetermined holder and measured using a powder X-ray diffractometer mini Flex 600 (trade name, manufactured by Rigaku, similar equipment is used in other examples). did. The pigment obtained above had peaks at 27.3°, 13.6° and 5.6° as 2θ values by powder X-ray diffraction. Also, the intensity ratio of these peaks was about 76:about 73:100.

Further, when the pigment particles of the obtained quinacridone solid solution pigment were observed with a transmission electron microscope, the average particle diameter of the long axis was about 59 nm. This is called solid solution pigment 1. The average particle diameter of the long axis in this specification is obtained by observing the pigment particles with a transmission electron microscope, randomly selecting 200 pigment particles, measuring the particle diameter of the long axis of each particle, and obtaining each It is the arithmetic mean of the particle measurements.

(Example 2)
As in Example 1, 84.0% polyphosphoric acid was made. Then, when the internal temperature has decreased to about 100° C., add 6.12 g of 2,5-di(p-toluidino)terephthalic acid (DM-DATA), then 14.28 g of 2,5-dianilinoterephthalic acid (DATA). was added gradually. After completion of the addition, a cocyclization reaction was carried out at 120° C. for 4 hours. After completion of the reaction, put the reaction solution obtained above into a 500 ml beaker filled with 200 ml of room temperature water, filter and wash with water, transfer to a 1 L beaker, add 500 ml of water, stir, and remove caustic soda. and the pH was adjusted to 7-8. This was filtered and washed with hot water to obtain a crude quinacridone solid solution containing water. The crude quinacridone solid solution had a mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone of 70:30.

The wet crude quinacridone solid solution obtained above was dried at 80° C. overnight to a moisture content of less than 1%. After drying, it was pulverized to obtain 17.9 g of crude quinacridone solid solution powder. Observation of the obtained powder with a transmission electron microscope revealed that the average particle size of the long axis was about 20 nm.

Next, the crude quinacridone solid solution was pigmented in the same manner as in Example 1 using dimethyl sulfoxide (DMSO), which does not dissolve the powder, as the liquid medium. Specifically, 7.0 g of crude quinacridone solid solution powder and 52.5 g of dimethyl sulfoxide were placed in a 100 ml separable flask, heated to 100° C. over 30 minutes, and heat-treated at the same temperature for 3 hours. pigmented.

After heating and pigmenting as described above, the liquid medium was cooled to a temperature of 40° C. or less. After cooling, a quinacridone-based pigment derivative was added and stirred as described below. Specifically, after cooling the liquid medium to 40° C. or lower, 0.21 g of 2-phthalimidomethylquinacridone powder, which is a quinacridone pigment derivative, was added and the mixture was further treated for 1 hour while stirring. After addition of the pigment derivative, the mixture was filtered, washed with hot water and water until the filtrate became colorless, and then dried at 80° C. to obtain a powder of the quinacridone solid solution pigment of this example.

The solid solution pigment to which the pigment derivative obtained above was added had peaks at 27.4°, 13.6° and 5.8° in terms of 2θ values according to powder X-ray diffraction. Also, the peak intensity ratio was about 61:about 75:100. Observation of the pigment particles with a transmission electron microscope revealed that the average particle diameter of the long axis was about 60 nm. This is simply called a solid solution pigment 2.

(Example 3)
First, 65.6 g of 85% phosphoric acid was weighed into a 100 ml separable flask, and 98.7 g of phosphoric anhydride was added to prepare 84.0% polyphosphoric acid. Then, when the internal temperature has decreased to about 100° C., add 14.28 g of 2,5-di(p-toluidino)terephthalic acid (DM-DATA) and then 6.12 g of 2,5-dianilinoterephthalic acid (DATA). was added gradually. After completion of the addition, a cocyclization reaction was carried out at 120° C. for 4 hours. After completion of the reaction, 400 ml of room temperature water was filled in a 1 L beaker, and the reaction solution obtained above was added. After filtration and washing with water, the mixture was transferred to a 1 L beaker, 800 ml of water was added and stirred, and caustic soda was added to adjust the pH to 7-8. This was filtered and washed with hot water to obtain a crude quinacridone solid solution containing water. The crude quinacridone solid solution had a mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone of 30:70.

The wet crude quinacridone solid solution obtained above was dried at 80° C. overnight to a moisture content of less than 1%. After drying, it was pulverized to obtain 18.1 g of crude quinacridone solid solution powder. Observation of the obtained powder with a transmission electron microscope revealed that the average particle size of the long axis was about 20 nm.

Next, using dimethyl sulfoxide (DMSO) as a liquid medium that does not dissolve the above powder, the crude quinacridone solid solution was pigmented as follows. Specifically, 7.0 g of the crude quinacridone solid solution powder obtained above and 70.0 g of dimethyl sulfoxide were placed in a 100 ml separable flask, heated to 105° C. over 1 hour, and heated to 105° C. over 1 hour. It was heat-treated for a period of time to form a pigment.

After heating and pigmenting as described above, the liquid medium was cooled to a temperature of 70° C. or lower. After further cooling, the quinacridone-based pigment derivative was added and stirred in the following manner. Specifically, after cooling to 70° C. or less, 0.21 g of 2-phthalimidomethylquinacridone powder, which is a quinacridone pigment derivative, was added and the mixture was further treated for 1 hour while stirring. After addition of the pigment derivative, the mixture was filtered, washed with hot water and water until the filtrate became colorless, and then dried at 80° C. to obtain a powder of the quinacridone solid solution pigment of this example.

The pigment obtained above has peaks at 27.3°, 13.8° and 5.6° in terms of 2θ values by powder X-ray diffraction, and the peak intensity ratio of these peaks is about 76: It was about 65:100. Observation of the pigment particles with a transmission electron microscope revealed that the average particle diameter of the long axis was about 60 nm. This is simply called solid solution pigment 3 .

[Comparative Examples 1 to 3]
(Comparative example 1)
In this comparative example, after the crude quinacridone solid solution in which the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone was 50:50 in Example 1 was pigmented, a quinacridone pigment derivative was added and treated. A quinacridone solid solution pigment powder of this comparative example was obtained in the same manner as in Example 1, except that the drying was not performed.

The quinacridone solid solution pigment obtained above has peaks at 27.3°, 13.6° and 5.6° in terms of 2θ values obtained by powder X-ray diffraction, and the peak intensity ratio is about 78: about It was 73:100. Further, when the pigment particles of the quinacridone solid solution pigment obtained above were observed with a transmission electron microscope, the average particle diameter of the long axis was about 60 nm. This is simply referred to as Comparative Pigment 1. The evaluation results of the color of the colored product obtained when the comparative pigment 1 obtained above is used will be collectively described later together with the examples.

(Comparative example 2)
In this comparative example, after the crude quinacridone solid solution in which the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone was 70:30 in Example 2 was pigmented, a quinacridone pigment derivative was added and treated. A quinacridone solid solution pigment powder of this comparative example was obtained in the same manner as in Example 2, except that the drying was not performed.

The quinacridone solid solution pigment obtained above has peaks at 27.4°, 13.6° and 5.8° in terms of 2θ values by powder X-ray diffraction, and the peak intensity ratio is about 61: It was about 73:100. Further, when the pigment particles of the quinacridone solid solution pigment obtained above were observed with a transmission electron microscope, the average particle diameter of the long axis was about 61 nm. This is simply referred to as Comparative Pigment 2.

(Comparative Example 3)
In this comparative example, after the crude quinacridone solid solution in which the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone was 30:70 in Example 3 was pigmented, a quinacridone pigment derivative was added and treated. A quinacridone solid solution pigment powder of this comparative example was obtained in the same manner as in Example 3, except that the drying was not performed.

The pigment obtained above has peaks at 27.3°, 13.9° and 5.6° as 2θ values by powder X-ray diffraction, and the peak intensity ratio is about 75: about 65. : 100. Observation of the pigment particles with a transmission electron microscope revealed that the average particle diameter of the long axis was about 59 nm. This is simply referred to as Comparative Pigment 3.

<Evaluation 1: Color of quinacridone solid solution pigment>
Using the quinacridone solid solution pigments obtained in Examples 1 to 3 and Comparative Examples 1 to 3, respectively, two types of paints obtained as follows were used to prepare a primary color coating film and a light color coating film. Then, the L ^* a ^* b ^* values of each coating film were measured to evaluate the color. Table 1 summarizes the results obtained.

1. Preparation of paint (1) Preparation of base paint Using each pigment of Examples and Comparative Examples, 0.8 g of the pigment, alkyd-melamine resin (trade name: 106-3700 Lacquer Clear Art Clear; manufactured by Isamu Paint Co., Ltd.) ), 5.0 g of a thinner containing toluene, ethyl acetate and butanol (trade name: Nippe 2500 thinner, manufactured by Nippon Paint Co., Ltd.), and 50.0 g of glass beads were placed in a plastic container. After dispersing this mixture with a paint shaker for 1 hour, 35.0 g of the above alkyd-melamine resin and 4.0 g of the above thinner were added and dispersed for 10 minutes to obtain a dispersion of each pigment. 10.0 g of each of the resulting dispersions and 20.0 g of the alkyd-melamine resin were placed in a plastic container, dispersed and mixed with Mazerustar (trade name, manufactured by Kurabo Industries, Ltd.), and a base paint (primary color paint) containing each pigment was prepared. ).

(2) Preparation of light-colored paint Using each pigment of Examples and Comparative Examples, 0.8 g of the pigment, 5.0 g of the above alkyd-melamine resin, 5.0 g of the above thinner, and glass beads 50 g was charged in a plastic container. After dispersing this mixture with a paint shaker for 1 hour, 35.0 g of the alkyd-melamine resin and 4.0 g of the thinner were added and dispersed for 10 minutes to obtain a dispersion of each pigment. 10.0 g of each of the resulting dispersions and 20.0 g of a white ink containing titanium oxide as a main component (trade name: 10 Super 300 White, manufactured by Nippon Paint Co., Ltd.) were placed in a plastic container and dispersed and mixed using a Mazerustar. A light-colored paint containing a pigment of

2. Preparation of Colored Product and Hue Evaluation (1) Each of the base paints prepared was spread on a colored paper using a 6 mil applicator, and the colored paper was dried at room temperature for several hours. Color-developed paper (hereinafter referred to as primary color coating film) prepared using the paint containing each pigment of Examples and Comparative Examples prepared in this manner is visually observed and the hue is compared and evaluated using a colorimeter. did. The results are shown in Table 1. In addition, visual observation is a relative evaluation.

(2) The light-colored paint thus prepared was spread on color-developing paper using a 6-mil applicator, and the color-developing paper was dried at room temperature for several hours. The hue of the thus-prepared exhibit (hereinafter referred to as a light-colored coating film) was also evaluated in the same manner as described above, and the results are shown in Table 1.

(3) For the primary color coating film and light color coating film obtained using each pigment of Examples 1 to 3 and Comparative Examples 1 to 3 prepared above, the colorimetric values measured using a colorimeter are shown. 1. At that time, the color was measured using a spectrophotometer CM-3600d (trade name, manufactured by Konica Minolta). L ^* is lightness, C is chroma, and chroma C ^* was obtained by √(a ^* ) ² +(b ^* ) ² .

The only difference between Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3 is whether or not a quinacridone-based pigment derivative was added to or treated with the pigment. As shown in Table 1, solid solution pigments 1 to 3 of Examples 1 to 3 in which a quinacridone-based pigment derivative was added and a quinacridone-based pigment derivative was used in combination, and Comparative Examples 1 to 3 in which a quinacridone-based pigment derivative was not used in combination. It was confirmed that the hue (tint) did not change significantly between the comparative pigments 1 to 3 of . Further, the difference between solid solution pigments 1 to 3 of Examples 1 to 3 is the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone. Regarding this point, as shown in Table 1, a large difference was observed especially in the value of b ^* . This is consistent with the results of visual observation, and the smaller the value of b ^* , the more blue-shifted the hue becomes, and the larger the value of b ^* , the more yellowish the hue becomes. Then, in the case of the solid solution pigment 1 of Example 1 having a mass ratio of 50:50, it became an intermediate, unique purple hue. For reference, when a pigment was prepared by mixing unsubstituted quinacridone and 2,9-dialkylquinacridone at a mass ratio of 50:50, the resulting pigment had an intermediate hue. It was confirmed by visual observation that the clearness was clearly inferior to that of the solid solution pigment 1 of Example 1.

[Influence on water-based pigment dispersion due to difference in addition timing and amount of quinacridone pigment derivative]
[Examples 4-6, Comparative Examples 4-6]
(Preparation of simple aqueous pigment dispersion)
The mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone in Example 2, in which 3% of a quinacridone pigment derivative is added after heating a crude quinacridone solid solution to form a pigment, cooling the liquid medium, and 2,9-dialkylquinacridone is 70. An aqueous pigment dispersion of Example 5 was obtained in the following manner using the solid solution pigment 2 of :30. Specifically, 5 parts of the solid solution pigment 2 of Example 2, 6.17 parts of a pigment dispersant, 0.75 parts of diethylene glycol monobutyl ether (also known as butyl diglycol, abbreviated as BDG) as a liquid medium, and water was compounded at 10.68 parts to prepare a pre-mill base. The pigment dispersant used above is a styrene/2-ethylhexyl acrylate/acrylic acid (mass ratio: 50/30/20) copolymer having a number average molecular weight of 7000 and an acid value of 155 mgKOH/g. An aqueous solution of neutralized ammonia (30% solids) was used. Subsequently, the pre-mill base obtained above was subjected to a dispersion treatment using a cooling fan equipped disperser "DAS H 200" (trade name, manufactured by LAU). After 4 hours of dispersion, the dispersion was terminated to obtain a millbase.

The mill base obtained above was diluted with water so that the pigment content was 14% to obtain an aqueous pigment dispersion of Example 5, in which a quinacridone solid solution pigment containing a pigment derivative was dispersed. rice field.

The average particle size of the aqueous pigment dispersion of Example 5 obtained above was measured (25° C.) using a particle size analyzer “NICOMP 380ZLS-S” (particle sizing system, manufactured by PSS). Further, the liquid chromaticity of the aqueous pigment dispersion was measured using a spectrophotometer "U-3310 spectrophotometer" (trade name, manufactured by Hitachi High Technology Co., Ltd.). L ^* is lightness, C is chroma, and chroma C ^* was obtained by √(a ^* ) ² +(b ^* ) ² . The viscosity of the aqueous pigment dispersion was measured at a temperature of 25° C. using VISCOMETER (trade name, manufactured by Toki Sangyo Co., Ltd.). Table 2 summarizes the results of the formulation and physical properties of the aqueous pigment dispersion of Example 5 obtained above.

Regarding the quinacridone solid solution pigment in which the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 70:30, used in the preparation of the aqueous pigment dispersion of Example 5, the production method is as follows. Aqueous pigment dispersions of Examples 4 and 6 and aqueous pigment dispersions of Comparative Examples 4 to 6 were obtained using the quinacridone solid solution pigments obtained by alternately producing them. Then, the effect of the conditions of the method for producing the quinacridone solid solution pigment on the properties of the aqueous pigment dispersions obtained by dispersing these pigments was investigated.

Specifically, the quinacridone solid solution pigment used in the aqueous pigment dispersions of Examples 4 and 6 of the present invention was the same as in Example 2, except that the amount of the quinacridone pigment derivative used in the production was changed. Two types of quinacridone solid solution pigments were prepared in a similar manner. Next, using the two types of prepared quinacridone solid solution pigments, the aqueous pigment dispersions of Examples 4 and 6 were prepared in the same manner as in the above-described method for obtaining the aqueous pigment dispersion of Example 5. I got the liquid. Specifically, in the aqueous pigment dispersion of Example 4, a quinacridone solid solution pigment prepared by adding 1% of a quinacridone pigment derivative was used. In the aqueous pigment dispersion of Example 6, a quinacridone solid solution pigment prepared by adding 5% of a quinacridone pigment derivative was used.

In order to compare with the aqueous pigment dispersions of Examples 4 to 6 obtained using the quinacridone solid solution pigments obtained by the production method of the present invention, the following three types of quinacridone solid solution pigments were prepared by the conventional production method. did. Aqueous pigment dispersions of Comparative Examples 4 to 6 were then obtained in the same manner as in Examples 4 to 6 using quinacridone solid solution pigments obtained by a conventional production method. The comparative quinacridone solid solution pigments used in the aqueous pigment dispersions of Comparative Examples 4 to 6 were prepared by a production method different in the following points. That is, the quinacridone solid solution pigment for comparison was obtained by heat-treating powdery crude quinacridone solid solution in a liquid medium at 100° C. for 3 hours to form a pigment. It is a solid solution pigment obtained by adding a quinacridone pigment derivative in a heated state. In contrast, in the production method of the present invention, after the crude quinacridone solid solution is heated in a liquid medium to form a pigment, the liquid medium is cooled, and then a quinacridone pigment derivative is added to produce a quinacridone to which the quinacridone pigment derivative has been added. A solid solution pigment is obtained. The comparative quinacridone solid solution pigment used in each of the aqueous pigment dispersions of Comparative Examples 4 to 6 was the amount of the quinacridone solid solution pigment used in each of the aqueous pigment dispersions of Examples 4 to 6 and the added amount of the quinacridone pigment derivative ( 1%, 3%, 5%).

(Evaluation of Simple Aqueous Pigment Dispersion)
The aqueous pigment dispersions of Examples 4 and 6 obtained above and the aqueous pigment dispersions of Comparative Examples 4 to 6 were dispersed in the same manner as the aqueous pigment dispersion of Example 5 described above. The average particle size of the pigments contained therein, the viscosity of the pigment dispersion, and the liquid chromaticity of the pigment dispersion were measured. Table 2 summarizes the obtained results.

As shown in Table 2, the basic difference between the aqueous pigment dispersions of Examples 4-6 and the corresponding aqueous pigment dispersions of Comparative Examples 4-6 is the quinacridone solid solution pigment used in the pigment dispersions. It is only the timing of addition of the quinacridone-based pigment derivative during the production of . Specifically, in the case of the quinacridone solid solution pigment used in the pigment dispersion liquid of the example of the present invention, the powdery crude quinacridone solid solution is heated in a liquid medium in which the crude quinacridone solid solution is not dissolved to form a pigment. , the liquid medium is cooled to a temperature of 40°C or less, and then the quinacridone pigment derivative is added for treatment. In contrast, in the aqueous pigment dispersions of Comparative Examples 4 to 6, a quinacridone-based pigment derivative was added when the powdery crude quinacridone solid solution was heated in a liquid medium to form a pigment, and the pigment derivative coexisted. to obtain a quinacridone solid solution pigment.

As described above, the difference between the aqueous pigment dispersions of the examples of the present invention and the corresponding aqueous pigment dispersions of the comparative examples is basically only the timing of addition of the quinacridone-based pigment derivative in the quinacridone solid solution pigment used. is. As shown in Table 2, the present inventors have found that the aqueous pigment dispersions of Examples are different from the aqueous pigment dispersions of Comparative Examples in the following points, although the difference is only in this point. It has been found that the properties are excellent. Specifically, the average particle size (nm) of the quinacridone solid solution pigment in the aqueous pigment dispersion is stable without being affected by the amount of the quinacridone pigment derivative added in the pigment dispersion of the examples. In contrast, in the case of the pigment dispersion of the comparative example, changing the addition amount of the quinacridone pigment derivative did not affect the average particle size (nm) of the solid solution pigment in the pigment dispersion. and did not reach a stable size. Further, when comparing the liquid chromaticities measured for the aqueous pigment dispersions of Examples and Comparative Examples, as shown in Table 2, compared to the chroma C ^* values of the aqueous pigment dispersions of Examples 4 to 6, In the aqueous pigment dispersions of Comparative Examples 4 to 6, there was a tendency for the chroma C ^* value of the liquid chromaticity to decrease. This tendency for the chroma C ^* value of the liquid chromaticity to decrease was more pronounced as the amount of the quinacridone-based pigment derivative added increased. On the other hand, in the case of the aqueous pigment dispersions of the examples of the present invention, regardless of the amount of the quinacridone pigment derivative added, the chromaticity C ^* value of the liquid chromaticity is high and stable.

The inventors of the present invention consider the reason why the above effects are obtained as follows. That is, in the conventional production method, a quinacridone-based pigment derivative is added during the pigmentation process of heating to form a pigment, whereas in the method for producing a quinacridone solid solution pigment of the present invention, a liquid is added after the pigmentation process. Since the medium is cooled and then the quinacridone-based pigment derivative is added to the quinacridone solid solution pigment, the pigment particles are already arranged at the time of addition. It is believed that the average particle size and liquid chromaticity of the liquid did not change. As for the color, the quinacridone solid solution pigments used in Examples 4 to 6 are the same as the quinacridone solid solution pigments used in Comparative Examples 4 to 6, and are not different.

[Application of the quinacridone solid solution pigment of the present invention to water-based pigment ink for inkjet]
(Preparation of water-based pigment ink 1 for simple inkjet)
Next, a water-based pigment ink for simple inkjet was prepared, and the effect of applying the quinacridone solid solution pigment of the present invention to the water-based pigment ink for inkjet was examined. First, using the previously prepared quinacridone solid solution pigment of Example 1, an aqueous pigment dispersion 1 was obtained in the same manner as the aqueous pigment dispersions of Examples 4 to 6 described above. The quinacridone solid solution pigment of Example 1 was obtained by adding 3% of a quinacridone pigment derivative to the quinacridone solid solution pigment in a mass ratio of 50:50 between unsubstituted quinacridone and 2,9-dialkylquinacridone.

Using the aqueous pigment dispersion 1 obtained above, a simple inkjet aqueous pigment ink 1 (hereinafter referred to as inkjet ink 1) was obtained. Specifically, with respect to 6.43 parts of the aqueous pigment dispersion, 0.45 parts of BDG, 0.9 parts of triethylene glycol monobutyl ether (BTG), 3.06 parts of glycerin, surfactant 0.18 part of "Surfinol 465" (trade name, manufactured by Air Products) and water were added to adjust the total amount to 18 parts, and the mixture was sufficiently stirred to obtain ink 1 for inkjet.

The average particle size of the pigment in the resulting inkjet ink 1 was measured (at 25° C.) in the same manner as in the aqueous pigment dispersion described above, and found to be 122 nm. Further, the viscosity of inkjet ink 1 measured by the same method as that used for the water-based pigment dispersion described above was 3.51 mPa·s.

(Preparation of simple inkjet water-based pigment inks 2 to 6)
Using the previously prepared quinacridone solid solution pigments of Examples 2 and 3, respectively, aqueous pigment dispersions 2 and 3 were obtained in the same manner as the above aqueous pigment dispersion 1 was obtained. The quinacridone solid solution pigment used in Example 2 had a mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone of 70:30, and the quinacridone solid solution pigment used in Example 3 had a mass ratio of is 30:70. The quinacridone solid solution pigments of Examples 2 and 3 were both prepared by heating a crude quinacridone solid solution to form a pigment, cooling the liquid medium, and adding 3% of a quinacridone pigment derivative.

Further, aqueous pigment dispersions 4 to 6 were prepared in the same manner as the above aqueous pigment dispersion 1 except that the quinacridone solid solution pigments of Comparative Examples 1 to 3 were used instead of the quinacridone solid solution pigments of Examples 1 to 3. got The quinacridone solid solution pigments of Comparative Examples 1-3 used in aqueous pigment dispersions 4-6 were prepared in the same manner as the quinacridone solid solution pigments of Examples 1-3, except that no quinacridone pigment derivative was added. It is a thing.

A simple inkjet was prepared in the same manner as described above, except that the aqueous pigment dispersions 2 to 6 obtained above were used instead of the aqueous pigment dispersion 1 used in the preparation of the inkjet ink 1 described above. Water-based pigment inks 2 to 6 (hereinafter referred to as inkjet inks 2 to 6) were prepared. Then, the average particle size (nm) of the pigment contained in each of the obtained ink jet inks 2 to 6 was measured (25° C.) in the same manner as in the ink jet ink 1. In addition, the viscosity (mPa·s) of inkjet inks 2 to 6 was measured by the same method as that used for the water-based pigment dispersion described above. The results are summarized in Table 3 and shown.

(Evaluation of water-based pigment ink for simple inkjet)
1. Evaluation of Dispersion Stability and Storage Stability For each of the inkjet inks 1 to 6 prepared above, the dispersion stability and storage stability were evaluated according to the following method and criteria. First, for each inkjet ink, the viscosity (mPa·s) and the average particle size (nm) were respectively measured before the test and after being left at 70° C. for 7 days. Then, using these measured values, the rate of change (%) in viscosity and particle size that occurred during the standing period was calculated. Table 3 collectively shows the average particle size at the initial stage and after 7 days, and the rate of change thereof. The rate of change was obtained by calculating the difference from the formula (value after 7 days)-(initial value), dividing the difference by the initial value, and describing it using 100 percent (%). Then, regarding the evaluation of the dispersion stability and storage stability of inkjet inks 1 to 6, regarding the change in particle size, the case where the change rate of the particle size is ± 5% or less is indicated by ◎, and the others are indicated by ×. 3. In addition, changes in viscosity are shown in Table 3 as ⊚ when the rate of change in viscosity is ±2% or less, and as x when otherwise.

2. Quality evaluation of printed matter The inkjet inks 1 to 6 prepared above are filled in ink cartridges, respectively, and using an inkjet printer, (i) dedicated photo glossy paper (PGPP) and (ii) plain paper Each type of paper was printed in photo mode to obtain prints. As the inkjet printer, "PM4000PX" (trade name, manufactured by Seiko Epson Corporation) was used. As plain paper, "Xerox Business 4200 Paper" (trade name, manufactured by Xerox, USA) was used. As a result, it was confirmed that any of the water-based pigment inks could be ejected from an inkjet nozzle without any problem.

The quality of each print obtained by printing as described above was evaluated using a spectrophotometer “i1 Basic Pro” (trade name, manufactured by X-rite). Specifically, the chroma C ^* and the optical density (OD value) of each printed material obtained were measured and evaluated with a spectrophotometer under the following conditions. Table 4 shows the measurement results. In addition, the results of visual observation of color are also shown. Incidentally, for both the optical density (OD value) and the chroma C ^* , it can be evaluated that the larger the numerical value, the better.

[Measurement condition]
Optical density (OD value) of plain paper: Average value of 3 measurements each at 6 locations Optical characteristics of plain paper (chroma C ^* ): Average value of 1 measurement each of 6 locations Optical density (OD value) of dedicated photographic glossy paper Value): Average value of one measurement each at three locations Optical characteristics of exclusive glossy photo paper (chroma C ^* ): Average value of one measurement each at three locations

As shown in Table 4, each of the prints obtained as described above has a different tint depending on the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone, and is printed on plain paper. It was confirmed that good images exhibiting high optical densities were obtained on both the paper and the glossy paper. As shown in Table 4, especially in the printed matter formed on glossy paper, the printed matter using the ink using the quinacridone solid solution pigment of the example to which the quinacridone pigment derivative was added was superior to the ink of the comparative example to which the quinacridone pigment derivative was not added. It was observed that the OD value tended to be higher than the printed matter used. Further, as shown in Table 4, the average particle size of the pigment in the ink was lower than that of the ink using the quinacridone solid solution pigments of Examples 1 to 3, which was the mass of the unsubstituted quinacridone and the 2,9-dialkylquinacridone. Regardless of the ratio, there was a tendency for the particle diameters of the pigments in the ink to be uniform. Moreover, although the inks using the quinacridone solid solution pigments of Examples 1 to 3 used the quinacridone solid solution pigments to which the quinacridone pigment derivatives were added, compared with the comparative examples in which the quinacridone pigment derivatives were not added, In particular, it was confirmed that there was no tendency for the chroma C ^* to decrease.

Claims (4)

A step of producing a crude quinacridone solid solution, a drying step of drying the crude quinacridone solid solution, a pigmentation step of heating the dried crude quinacridone solid solution in a liquid medium to form a pigment, and treating the pigmented pigment with a quinacridone pigment derivative. and a processing step to
In the process for producing the crude quinacridone solid solution, diarylaminoterephthalic acid and dialkylarylaminoterephthalic acid are subjected to a co-cyclization reaction in polyphosphoric acid so that the mass ratio of unsubstituted quinacridone and 2,9-dialkylquinacridone is 85: Obtaining a crude quinacridone solid solution in a hydrous state containing water in a solid solution of 15 to 50:50 or 20:80 to 50:50,
in the drying step, drying the hydrous crude quinacridone solid solution to a moisture content of less than 1% to obtain a powdery crude quinacridone solid solution;
In the pigmentation step, without adding a quinacridone pigment derivative, the powdery crude quinacridone solid solution obtained above is heated at a temperature above 70° C. to 120° C. in a liquid medium that does not dissolve the crude quinacridone solid solution. pigmented ,
In the treatment step, after cooling the heated liquid medium containing the quinacridone solid solution after pigmentation to a temperature of 70° C. or less, a quinacridone-based pigment derivative is added, and the quinacridone-based pigment derivative is added to the quinacridone solid solution pigment. A method for producing a quinacridone solid solution pigment, characterized in that a quinacridone solid solution pigment is obtained. The diarylaminoterephthalic acid is 2,5-dianilinoterephthalic acid, the dialkylarylaminoterephthalic acid is 2,5-di(p-toluidino)terephthalic acid, and the quinacridone pigment derivative is 2. The method for producing a quinacridone solid solution pigment according to claim 1, wherein the quinacridone is 2-phthalimidomethylquinacridone. 3. The method for producing a quinacridone solid solution pigment according to claim 1, wherein the liquid medium is at least one selected from the group consisting of dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, ethanol, propanol, butanol and ethylene glycol. The method for producing a quinacridone solid solution pigment according to any one of claims 1 to 3, wherein the obtained quinacridone solid solution pigment is used for inkjet ink.